The present disclosure generally relates to closure lockdown assemblies for use in an automotive vehicle, wherein the closure lockdown assemblies include the use of active materials for reversible on-demand lockdown of the closure to the vehicle.
Most motor vehicles employ one or more hingeable closures, an example being a hood or bonnet, which is disposed in a region between the passenger compartment and the forward bumper of the motor vehicle, or a trunk lid or boot, which is between the passenger compartment and the rearward bumper of the motor vehicle, or a door for entering and exiting the vehicle, among other closures. The hingeable closures generally provide a mechanism for accessing the underlying compartment such as an engine or storage compartment and/or for permitting entry and exit of an occupant or object from the vehicle. Focusing on the vehicle hood, it is typically formed of a relatively thin sheet of metal or plastic that is molded to the appropriate contour corresponding to the overall vehicle body design. The exterior of the hood portion, which constitutes the show surface thereof, is typically coated with one or more coats of primer and paint for enhancing both the aesthetic character and the corrosion resistance of the underlying material. Due to the relatively thin nature of the material forming the hood portion, a support structure such as a contoured plate with stamped rib supports typically extends across the underside of the hood portion so as to provide a degree of dimensional stability to the structure.
Vehicle closure latch systems are primarily used for locking down the closure generally at single discrete point opposite the pivot point of the closure. The latch system typically includes a striker on the closure, a primary latching member on the vehicle body engageable with the striker to hold the pivotable closure in the closed position, and a secondary latching member on the vehicle body in the path taken by the striker from the latched condition. The secondary latching member acts as a redundant safety device to prevent the closure from opening in the event that the primary latching member might disengage during service, such as may be desired for vehicle hoods.
In the case of hoods and trunk lids, very often the primary latching member is cable-operated from inside the vehicle. The secondary latching member is directly operated (e.g. by a handle). The secondary latching member usually has an actuating handle that is accessible to a person's fingers when the person is standing in front of the vehicle. The actuating handle must be pushed or pulled in a specific direction in order to release the secondary latching member from the striker.
Since the latch system is disposed at a single discrete point and is static in its design, the current system is not adaptable to changing conditions. For example, it would be desirable to have a closure lockdown mechanism that can alter load paths or provide energy absorption properties such as may be beneficial during an impact event. Moreover, it is desirable to have a plurality of lockdown attachments of the hood to the vehicle body so as to provide complete securement about the perimeter of the hood to the vehicle. These comments in general hold true for most other types of vehicle closures, e.g., lift gates, tail gates, sunroofs, doors, trunks, hoods, and the like.